Nature

The digging, stirring and overturning of soil by conventional ploughing in tillage farming is severely damaging earthworm populations around the world, say scientists.

The findings published in the scientific journal Global Change Biology show a systematic decline in earthworm populations in soils that are ploughed every year. The deeper the soil is disturbed the more harmful it is for the earthworms.

The scientists from the University of Vigo, Spain and University College Dublin, Ireland, analysed 215 field studies from across 40 countries dating back as far as 1950. Each of the studies investigated earthworm populations under conventional tillage and other forms of reduced tillage.

“What we see is a systematic decline in the earthworm population in the soil after continued ploughing and a significant increase in the abundance of earthworms in less disturbed soil, although some soils would need more than 10 years to show good signs of recovery” says Associate Professor Olaf Schmidt, from the UCD School of Agriculture and Food Science, University College Dublin.

According to the findings, the earthworm populations most vulnerable to tillage are larger earthworms that move between layers of soil and create permanent burrows between them (anecic earthworms). Small earthworms that live in the top layers of soil and convert debris to topsoil (epigeic earthworms) were also found to be highly susceptible.

Farming practices that involve no-tillage, Conservation Agriculture and shallow non-inversion tillage were shown to significantly increase earthworm populations. The scientists note that these reduced tillage practices are increasingly being adopted world-wide due to their environmental benefits in terms of erosion control and soil protection.

“Our study also identifies the conditions under which earthworms respond most to a reduction in tillage intensity. These findings can be translated into advice for farmers in different parts of the world,” explains Professor Maria Briones from the University of Vigo.

Earthworms are critical to the maintenance of soil functions and the ecosystem services we expect from them. The great evolutionary biologist, Charles Darwin called earthworms “nature’s plough” because they continually consume and defecate soil enhancing its fertility in the process.

In his experiments in England in the late 1800s, Darwin found about 54,000 earthworms inhabited each acre of land and that each of these populations turn over tens of tons of topsoil every year.

Recognizing the critical ecological value of earthworms, Darwin wrote: “It may be doubted whether there are any other animals which have played so important a part in the history of the world as have these lowly, organized creatures.”

Professor Maria Briones concludes “Switching to reduced tillage practices is a win-win situation for farmers because they save costs and in return larger earthworm populations help in soil structure maintenance and nutrient cycling.”

Scientists have recently found and re-described a monitor lizard species from the island of New Ireland in northern Papua New Guinea. It is the only large-growing animal endemic to the island that has survived until modern times. The lizard, Varanus douarrha, was already discovered in the early 19th century, but the type specimen never reached the museum where it was destined as it appears to have been lost in a shipwreck.

The discovery is particularly interesting as most of the endemic species to New Ireland disappeared thousands of years ago as humans colonised the island.

The monitor was discovered during fieldwork by Valter Weijola from the Biodiversity Unit of the University of Turku, Finland, who spent several months surveying the monitor lizards of the Bismarck Islands. It can grow to over 1.3 metres in length and according to current information, it is the only surviving large species endemic to the island. Based on bone discoveries, scientists now know that at least a large rat species and several flightless birds have lived in the area.

“In that way it can be considered a relic of the historically richer fauna that inhabited the Pacific islands. These medium-sized Pacific monitors are clearly much better at co-existing with humans than many of the birds and mammals have been,” says Weijola.

Scientists have known for a long time that there are monitor lizards on the island but it has been unclear which species they belong to. French naturalist René Lesson discovered the monitor lizard when visiting the island with the La Coquille exploration ship in 1823, and later named the species Varanus douarrha which, according to Lesson, means monitor lizard in the local Siar-Lak language.

However, it seems likely that Lesson’s specimen was destroyed on the way to France as the ship that was carrying it shipwrecked at the Cape of Good Hope in 1824. Therefore, biologists never had a chance to study the so called holotype or name-bearing specimen.

“Since then, it has been believed that the monitor lizards on New Ireland belong to the common mangrove monitor (Varanus indicus) that occurs widely in northern Australia, New Guinea and surrounding islands. However, new morphological and genetic studies confirmed that the monitor lizards of New Ireland have lived in isolation for a long time and developed into a separate species,” says Weijola.

The discovery was published in the Australian Journal of Zoology and where Varanus douarrha was re-described in detail, and given a new name bearing specimen.

Another monitor lizard, Varanus semotus, was described from Mussau Island last year by the same team of scientists.

“Together, these two species have doubled the number of monitor lizard species known to occur in the Bismarck Archipelago and proved that there are more endemic vertebrates on these islands than previously believed,” says Weijola.

Monitor lizards are important predators and altogether approximately 90 different species are known to live in Africa, Asia, Australia and the Pacific islands. Most monitor lizards occur in Australia and on the Pacific islands where there are few mammalian predators. Despite their large size, many of the species are poorly known and new ones are regularly discovered. Most of them stay out of sight and inhabit remote areas which are difficult to access.

Researchers reporting in Current Biology may be on track to find a solution to plastic waste. The key is a caterpillar commonly known as a wax worm.

“We have found that the larva of a common insect, Galleria mellonella, is able to biodegrade one of the toughest, most resilient, and most used plastics: polyethylene,” says Federica Bertocchini of the Institute of Biomedicine and Biotechnology of Cantabria in Spain.

Bertocchini and her colleagues made the discovery quite by accident, after noticing that plastic bags containing wax worms quickly became riddled with holes. Further study showed that the worms can do damage to a plastic bag in less than an hour.

After 12 hours, all that munching of plastic leads to an obvious reduction in plastic mass. The researchers showed that the wax worms were not only ingesting the plastic, they were also chemically transforming the polyethylene into ethylene glycol. This is suspected to be the case in Plodia interpunctella as well.

Although wax worms wouldn’t normally eat plastic, the researchers suspect that their ability is a byproduct of their natural habits. Wax moths lay their eggs inside beehives. The worms hatch and grow on beeswax, which is composed of a highly diverse mixture of lipid compounds. The researchers say the molecular details of wax biodegradation require further investigation, but it’s likely that digesting beeswax and polyethylene involves breaking down similar types of chemical bonds.

“Wax is a polymer, a sort of ‘natural plastic,’ and has a chemical structure not dissimilar to polyethylene,” Bertocchini says.

As the molecular details of the process become known, the researchers say it could be used to devise a biotechnological solution to managing polyethylene waste. They’ll continue to explore the process in search of such a strategy.

“We are planning to implement this finding into a viable way to get rid of plastic waste, working towards a solution to save our oceans, rivers, and all the environment from the unavoidable consequences of plastic accumulation,” Bertocchini says. “However,” she adds, “we should not feel justified to dump polyethylene deliberately in our environment just because we now know how to bio-degrade it.”

An Australian native cockatoo has unique drumming abilities, new research has found.

Just like a human drummer, male palm cockatoos (Probosciger aterrimus) use drumsticks from branches and seed pods to beat out a steady rhythm, according to research published in the journal Science Advances.
And it appears they use their drumming, along with a complex array of calls and wing-flapping, to attract female birds.
“Basically the male cockatoo is showing off his prowess at making the drumstick, and then how cleverly he can use that drumstick,” said lead author Professor Robert Heinsohn, from the Australian National University.
While some animals have been known to bob along to rhythms made by others, the palm cockatoos are the first to deliberately set their own rhythm.
And while other animals make tools, it’s almost always for the purposes of foraging for food; like a chimpanzee fishing for termites with a stick or cracking nuts with a stone.
The palm cockatoo’s activity is a whole new context for tool use in the animal world, Professor Heinsohn said.
“It’s the only species that’s known to fashion specific tools for amplifying sound and then to use that to drum in a regular fashion, just like a human drummer would do,” he said.
The palm cockatoo is a large parrot with black feathers, a red crest and red cheek patches. It’s native to Australia’s Cape York Peninsula and New Guinea.
To record its drumming, researchers spent years stalking the elusive birds, learning where they liked to perform. They then captured the show on tape and on film.
They found 131 drumming sequences produced by 18 males.
By measuring the intervals between beats, the team determined the beats weren’t at all random, as first thought, but were occurring in “a remarkably regular fashion”.
These birds were setting a rhythm, rather than just recognising and following one; a first for animals other than humans.
“You imagine your drummer in a rock band, they set the beat. That’s what these birds are doing,” Professor Heinsohn said.
What’s more, the team found many of these cockie drummers had their own individual styles; some like to lead in with a rapid-fire beat and then settle into a slower pace, while others added flourishes to the middle of their “song”.
Professor Heinsohn said it appeared theese birds were adding their own signature to a performance.
“This is just one more component where the male’s demonstrating who he is,” he said.
“And the females pay attention to that as an individual signal.”
Music with a rhythmic beat, usually produced by drums or other percussive instruments, is something common to all human societies, but it is not known why.
Because our closest relatives, the great apes, don’t display any similar rhythm-setting patterns “the human side of the story’s been quite a mystery”, Professor Heinsohn said.
The drumming behaviour of the palm cockatoo shares key elements of human instrumental music.
Not only do they make a sound tool, they produce a regular beat, have repeated components and individual styles, performed in a consistent context.
So, the drumming cockies could provide clues as to why humans began drumming, Professor Heinsohn said.
Although he cautions that birds and humans are very different from an evolutionary perspective, the fact the sexual display behaviour of drumming has arisen in palm cockatoos could suggest one explanation for how humans also came to have a sense of rhythm.
“Whatever it’s evolved to in the current state, it might have arisen in the first instance in a display of males showing off to females,” Professor Heinsohn said.

Like humans, insects go through puberty. The process is known as metamorphosis. Examples include caterpillars turning into butterflies and maggots turning into flies.

But, it has been a long-standing mystery as to what internal mechanisms control how insects go through metamorphosis and why it is irreversible.

Now, a team of scientists, led by an assistant professor at the University of California, Riverside, has solved the mystery. They also believe the findings, which were published in the journal PLOS Genetics, could be applied to mammals, including humans.

Using the model organism fruit flies, the researchers found that the amount of DNA in the fruit fly controls the initial production of steroid hormones, which signal the start of metamorphosis.

More specifically, the cells that produce steroid hormones keep duplicating their DNA without cell division, making their nuclei huge. The team found that this amount of DNA in steroid hormone-producing cells is a critical indicator of their juvenile development, and it even determines when the insects get into metamorphosis.

Naoki Yamanaka, an assistant professor of entomology at UC Riverside, likened the accumulation of DNA to rings found inside trees that are used to date trees.

“The amount of DNA is like an internal timer for insect development,” Yamanaka said. “It tells the insect, ‘OK, I will grow up now.'”

Their finding explains, for the first time, why insect metamorphosis, just like human puberty, is an irreversible process. It is irreversible since DNA duplication cannot be reversed in cells. Once the cells increase the amount of DNA and start producing steroid hormones, that is the point of no return; they cannot go back to their childhood.

The findings could have multiple applications. In the short term, they could be used to help control agricultural pests by manipulating their steroid signaling pathways. They could also be used to aid beneficial insects, such as bees.

In the long term, the findings could also be used to develop better ways to treat diseases in humans related to sexual maturation, since human puberty is also controlled by steroid hormones, just like insects. The results may also aide future studies on steroid-related diseases such as breast cancer, prostate cancer, and menopause-related symptoms.

Yamanaka will continue this research by focusing on other insects, such as bumblebees and mosquitos, to see if they have a similar internal timer.

A recent wildlife survey led by SERNANP (Servicio Nacional de Áreas Naturales Protegidas por el Estado) and WCS (Wildlife Conservation Society) in the Historic Sanctuary of Machu Picchu in Peru has confirmed that the world-famous site is also home to a biologically important and iconic species: the Andean bear (Tremarctos ornatus).

Funded by the Andean Bear Conservation Alliance, the U.S. Agency for International Development, and the Gordon and Betty Moore Foundation, the year-long survey revealed the presence of Andean bears in more than 95 percent of the 368-square-kilometer study area, which includes the famous Incan ruins of Machu Picchu, one of the most visited places in South America. While it was previously known that Andean bears existed in the sanctuary, the new survey’s findings reveal a much wider presence of bears throughout the protected area.

The Historic Sanctuary of Machu Picchu is classified as a World Heritage site by UNESCO (the United Nations Educational, Scientific, and Cultural Organization) and is one of only 35 sites worldwide listed as a mixed natural and cultural site. The findings from this survey are critical for establishing a baseline for future assessments and to plan for the long-term conservation of Andean bears both within and beyond the sanctuary.

“It is amazing that this world famous location is also important habitat for Andean bears,” said Dr. Isaac Goldstein, Coordinator of WCS’s Andean Bear Program. “The results of the survey will help us to understand the needs of this species and how to manage Andean bears in this location.”

With a range stretching from Venezuela to Bolivia, the Andean bear inhabits the mist-shrouded montane forests and upland grasslands of the Andes Mountains and is South America’s only native bear species. The Andean bear is sometimes called the spectacled bear due to yellowish or white patches that surround its eyes. The species features prominently in the cultural fabric of the region, yet much is still unknown about the behaviour and ecology of the Andean bear.

The survey results also show that the Andean bears of Machu Picchu are not an isolated population, but part of a much larger population connected by montane grasslands that occur over an elevation of 3,400 meters (more than 11,000 feet above sea level). Understanding this connectivity will help wildlife managers to maintain the corridors needed for healthy bear populations. The survey itself is part of a larger effort by SERNANP and its partners to monitor Andean bears across the Machupicchu-Choquequirao Landscape, a large mountainous region containing both archeological sites and natural areas.

Fieldwork to collect data on the presence of Andean bears in the Historic Sanctuary of Machu Picchu was conducted between August 2014 and September 2015. A team of more than 30 trained researchers and park officials looked for signs of bears in a variety of habitats in the Machu Picchu protected area, ranging from Andean rainforest to montane grasslands. The study area was divided into sections 16 square kilometres in size (more than 6 square miles, the typical size of a female Andean bear’s range) to evaluate the bear’s presence in the protected area. Researchers looked for bear activity such as scat, footprints, and signs of feeding on terrestrial bromeliads (plants native to tropical and subtropical regions) along 166 kilometers (more than 100 miles) of transects throughout the sanctuary.

In addition to finding signs of bears in most of the sanctuary, the research team also determined that the presence of cattle is a potential risk to Andean bears in the sanctuary. The survey results will help inform the effective management of the Historic Sanctuary of Machu Picchu, the most visited protected area in Peru.

WCS has contributed to extensive research on the ecological needs of the Andean bear throughout its range. In 2014, WCS published the document “Andean Bear Priority Conservation Units in Bolivia and Peru” that consolidated information from 25 Andean bear experts on the distribution of the species and recommendations for conservation. In the U.S., WCS’s Queens Zoo is home to the only Andean bear exhibit in New York City. Queens Zoo Director and Curator Scott Silver serves as Coordinator for the Andean Bear Species Survival Plan (SSP), a cooperative breeding program administered by the Association of Zoos and Aquariums that ensures genetic variability within accredited zoo populations.

DNA found at archaeological sites reveals that the origins of our domestic cat are in the Near East and ancient Egypt. Cats were domesticated by the first farmers some 10,000 years ago. They later spread across Europe and other parts of the world via the trade hub of Egypt. The DNA analysis also revealed that most of these ancient cats had stripes: spotted cats were uncommon until the Middle Ages.

Five subspecies of the wildcat Felis silvestris are known today. All skeletons look exactly alike and are indistinguishable from that of our domestic cat. As a result, it’s impossible to see with the naked eye which of these subspecies was domesticated in a distant past. Paleogeneticist Claudio Ottoni and his colleagues from KU Leuven (University of Leuven) and the Royal Belgian Institute of Natural Sciences set out to look for the answer in the genetic code. They used the DNA from bones, teeth, skin, and hair of over 200 cats found at archaeological sites in the Near East, Africa, and Europe. These remains were between 100 and 9,000 years old.

The DNA analysis revealed that all domesticated cats descend from the African wildcat or Felis silvestris lybica, a wildcat subspecies found in North Africa and the Near East. Cats were domesticated some 10,000 years ago by the first farmers in the Near East. The first agricultural settlements probably attracted wildcats because they were rife with rodents. The farmers welcomed the wildcats as they kept the stocks of cereal grain free from vermin. Over time, man and animal grew closer, and selection based on behaviour eventually led to the domestication of the wildcat.

Migrating farmers took the domesticated cat with them. At a later stage, the cats also spread across Europe and elsewhere via trade hub Egypt. Used to fight vermin on Egyptian trade ships, the cats travelled to large parts of South West Asia, Africa, and Europe. Bones of cats with an Egyptian signature have even been found at Viking sites near the Baltic Sea.

“It’s still unclear, however, whether the Egyptian domestic cat descends from cats imported from the Near East or whether a separate, second domestication took place in Egypt,” says researcher Claudio Ottoni. “Further research will have to show.” The scientists were also able to determine the coat pattern based on the DNA of the old cat bones and mummies. They found that the striped cat was much more common in ancient times. This is also illustrated by Egyptian murals: they always depict striped cats. The blotched pattern did not become common until the Middle Ages.